conversions.h

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#pragma once
 
#include "Math/math.h"
 
#include <Common/assertion.h>
#include <Common/primitive_type.h>
 
#include <cmath>
 
namespace ph
{
 
namespace lbconv
{
 
inline real alpha_to_variance(const real alpha)
{
    const real clampedAlpha = math::clamp(alpha, 0.0_r, 0.9999_r);
    const real alpha1p1 = std::pow(clampedAlpha, 1.1_r);
    return alpha1p1 / (1.0_r - alpha1p1);
}
 
inline real variance_to_alpha(const real variance)
{
    return std::pow(variance / (1.0_r + variance), 1.0_r / 1.1_r);
}
 
inline real g_to_variance(const real g)
{
    PH_ASSERT(0.0_r < g && g <= 1.0_r);
 
    return std::pow((1.0_r - g) / g, 0.8_r) / (1.0_r + g);
}
 
}// end namespace conversions
 
}// end namespace ph